Method of producing compound pellets containing wood flour

Abstract

While resin forming material and hygroscopic wood flour or wood flour containing water, which were fed to the feed port 23 of the intermeshing type two screw type screw side feeder 20, are being conveyed toward the intermeshing type twin screw extruder 1, they are somewhat kneaded and then introduced into the intermeshing type twin screw extruder 1. Resin forming material and hygroscopic wood flour or wood flour containing water, which have been introduced into the intermeshing type twin screw extruder 1, are melted and kneaded by the heat transmitted from the heating cylinder 2 and also by the heat generated in the process of shearing conducted by the rotating screws 3a, 3b. After that, they are extruded from the die 9 in the form of strands. Moisture and gas composed of volatile components generated in the process of melting and kneading are sucked by vacuum from the rear vent 6a arranged on the upstream side of the introducing port 5 and also sucked by vacuum from the vents 6b, 6c arranged on the downstream side of the introducing port 5, so that they can be discharged outside the apparatus.

What is claimed is: 
     
       1. A method of producing pellets using a screw type extruder having a heating cylinder with (1) an introducing port (2) an upstream vent located on an upstream side of said introducing port, and (3) a downstream vent located on a downstream side of said introducing port, said method comprising the steps of: introducing a thermoplastic material and a wood flour through said introducing port and into said heating cylinder;   conveying said thermoplastic material and said wood flour toward a downstream end of said heating cylinder to heat and knead said thermoplastic material and said wood flour; and   vacuum exhausting said heating cylinder via said upstream vent and said downstream vent.   
     
     
       2. A method of producing pellets according to claim 1, wherein the screw type extruder is an intermeshing type twin screw extruder. 
     
     
       3. A method of producing pellets according to claim 1, further comprising the steps of: extruding said thermoplastic material and said wood flour into strands; and   cutting said strands into pellets.   
     
     
       4. A method of producing pellets using a screw type extruder having a heating cylinder with (1) an introducing port (2) an upstream vent located on an upstream side of said introducing port, and (3) a downstream vent located on a downstream side of said introducing port, said method comprising the steps of: introducing a resin and a wood flour through said introducing port and into said heating cylinder;   conveying said resin and said wood flour toward a downstream end of said heating cylinder to heat and knead said resin and said wood flour; and   vacuum exhausting said heating cylinder via said upstream vent and said downstream vent.   
     
     
       5. A method of producing pellets according to claim 4, wherein the screw type extruder is an intermeshing type twin screw extruder. 
     
     
       6. A method of producing pellets according to claim 1, further comprising the steps of: extruding said resin and said wood flour into strands; and   cutting said strands into pellets.